The prehistoric practice of removing part of the skull to relieve pressure in the brain could prevent half of deaths from traumatic brain injury, a new study suggests.

Craniectomy, or trepanning, is a controversial technique where part of the skull cap is cut away to relieve dangerous swelling which can hinder blood supply and lead to death.

It is the oldest surgical technique ever found in the archaeological record, with examples found at European sites that are 8,500 years old. Experts think Stone Age healers used the method to revive men who sustained hunting injuries.

Now a study by Cambridge University has found that it significantly reduces the chance of death following a brain injury. Researchers recruited more than 400 people who had suffered a traumatic brain injury from car accidents, assaults or falls, across 19 countries.

Six months after their injury around one in four patients who had a crainectomy died, compared with nearly half of patients who just received medical management.

After 12 months, nearly half of patients who underwent the skull removal technique were able to live independently, compared with just one third of the control group.

Peter Hutchinson, Professor of Neurosurgery at the Department of Clinical Neurosciences at Cambridge, says: "Traumatic brain injury is an incredibly serious and life-threatening condition. From our study, we estimate that craniectomies can almost halve the risk of death for patients with a severe traumatic brain injury and significant swelling.

"Importantly, this is the first high-quality clinical trial in severe head injury to show a major difference in outcome. However, we need to be really conscious of the quality of life of patients following this operation, which ranged from vegetative state through varying states of disability to good recovery."

After surgery, patients typically need to wait several months before a bone graft can be used to close the skull again. Often, the original piece is reinserted in the gap.

Angelos Kolias, Clinical Lecturer at the department, added: "Doctors and families will need to be aware of the wide range of possible long-term outcomes when faced with the difficult decision as to whether to subject someone to what is a major operation."